A Gordon Research Conference on Prolactin will be held in Casa Sirena Marina Hotel, Oxnard, California, on February 3-7, 1992. This conference has been ongoing every two years since 1980, and has been drawing an audience of 110-130 participants. These include graduate students, postdoctoral fellows, and academic, government and industrial scientists from the USA and abroad who share a common interest in the various aspects of prolactin. About half of the participants has attended every Prolactin Gordon Conference since its inception. The participants, including the invited speakers and discussion leaders, are expected to stay in the meeting for the entire five days duration. Because of the unique evolutionary aspects of prolactin and its diversity of functions, the conference is of interest to an unusual broad range of disciplines, including comparative physiology, neurobiology, endocrinology, cellular and molecular biology, reproductive physiology, animal science and medicine. In accordance with the long tradition of the Gordon Research Conferences, the emphasis is on presentation of recent, unpublished observations, followed by long and probing discussions. Such a format fosters interactions between scientists from different disciplines and geographical locations and enables the field to remain progressive and viable. There is no other scientific meeting which fulfills this function. The conference is consisted of eight scientific sessions, 2-3 poster sessions, a banquet speaker, a business session, several informal meetings of groups with common interests and 2-3 social functions. The proposed scientific sessions are: 1) Prolactin and the neuroendocrine system, 2) Comparative aspects of prolactin, 3) Regulation of prolactin gene expression, 4) Decidual and placental lactogenic hormones, 5) Anterior pituitary lactotrophs, 6) Prolactin receptors, 7) Prolactin and the immune system, and 8) Prolactin secreting tumors and second messengers.